Are they usually clones?

I know with orchids, it is pretty much the norm when mass producing named varieties.

This is 'Carolina Breeze' which, in a fit of weakness, I picked up this past week. The colors are accurate in this pic:

This particular one had flowers that were brighter than the other CB's I saw there. Interestingly [to me at any rate], it did produce a much darker orange flower on Friday. I wondered if it was because I had put it on my balconey which gets lots of sun. [With orchids, amount of light buds are exposed to can affect bloom color.] However, I noted today that it has produced another bright flower like the one above.

These are a Yoder brothers introduction and offered as cuttings to the trade rooted or not, your choice. The only thing I can add is when my CB first comes out in the early morning it is deeper orange and then gets lighter (brighter)as the bloom goes through the day. I am used to several varieties having this habit so don't consider it unusual. I am not sure if this is whats happening with you or not just a guess from my observations of many different hibiscus varieties going through their daily bloom cycles.
Happy Growing David